Sanding and polishing tool



Dec'. l, 1942. D. n. EYsTER sANDING AND POLIsHING Too;J

Filed July 8, 1940 INVENTOR. DAME/ D. {VSH-'R BY j I ATTORNEY.

Patented Dec. 1, 1942 SANDING AND POLISHING TOOL Daniel D. Eyster, Milwaukee, Wis., assignor to Nash-Kelvinator Corporation, Kenosha, Wis., a corporation of Maryland Application July 8, 1940, Serial No. 344,314

8 Claims. (Q1. 51-170 This invention relates to a method of grinding, sanding or polishing surfaces preparatory to finishing and to tools and machines for carrying out the method.

The art of final finishing surfaces of all kinds and particularly automobile sheet metal surfaces has required that the surface be treated prior tothe application of any coats of finishing material thereto. The purpose of such treatment is to prevent the tool marksfsolder ller or the like from showing through the final coat of finishing material or appearing in the final finished product.

In order to accomplish this result it has been considered necessary, after filing and grinding away the most uneven portions of rough spots such as are caused, for example, by welding, to employ hand labor for dry or wet sanding the surface until the requisite state of smoothness necessary to satisfactory finishing has been developed. Manual labor of this type has been considered essential to the production of a satisfactory metal surface because of the factor of human aberration. A human being in sanding or polishing a surface will not make two strokes which are identical and will not therefore sand or polish one portion of the work more than another portion. It will bev understood that repeated sanding at one spot would tend to groove or otherwise to mar the surface, resulting in a condition which is sought to be avoided.

Even the grinding operation is a delicate one, and since it is done with a power tool, it is necessary that the operator keep the tool moving constantly in order to avoid excessive grinding at one spot. An efficient operator of such a power grinding tool is a rather highly skilled worker and must be taught to keep the tool in constant guided movement. Moreover, such work is extremely fatiguing because of the necessity for constant attention to the work and because of the physical eiort involved in constantly moving a heavy tool while the same is held against the work. f

It is an object of this invention to eliminate or substantially reduce the amount of hand labor necessary for preparing surfaces for nishing.

A further object of the invention is to eliminate the necessity for the use of highly skilled laborers in abrading a surface to be finished by A more specic object of the invention is to 55 acteristics.

provide an abrading machine in which the tool is rotated relatively rapidly about its own axis while being given a lsomewhat slower rotation about an eccentric axis to cause the tool to' move in an orbit.

Further objects will appear hereinafter as the description proceeds and will be pointed out more fully in connection with the appended claims.

In the drawing, of which there is one sheet,

and which is to be taken as illustrative rather Figure 2 is a horizontal sectional View takenv upon a plane as indicated by the line 2-2 of Figure 1 and looking in the direction of the arrows;

Figure 3 is a horizontal sectional View of the tool head shown in Figure 1 and taken upon a plane as indicated by the line 3 3 of Figure 1 and looking in the direction of the arrows;

Figure 4 is a vertical sectional view correspond# ing to Figure l but illustrating a modified form of abrading tool head; and, Figure 5 is a fragmentary view showing a power abrading sanding or polishing tool and the method of applying it to work.

Referring more particularly'to the drawing, in which similar parts are designated by similar reference characters, Figure 5 illustrates v'an abrading Wheel I0 which may be a rough grinding, a sanding tool or a polishing tool. Wheel l0 comprises a at disc which is attached,

' by means hereinafter described, to the face one edge portion of the wheel to come into con-1` tact with the work. This results in the wheel being tilted at a slight angle with respect to the plane of the work as shown in Figure 5.

With the abrading tool so positioned, it will` be recognized that rapid rotation of the disc would soon result in scuing or marring the surface if care is not taken by the operator to prevent the tool remaining too long in one spot.

The method which has previously been adoptedl by operator to accomplish this result is to move the tool back and forth in a substantially straight path and laterally to a new working area as the area being worked takes on the desired chan The present invention seeks to relieve the operator of this diiculty by providing a new method of abrading surfaces, which, although it could be carried out by hand, is more easily performed by a machine incorporating mechanism for giving the tool the desired mechanical movement. It has been found that a rotating motion of the tool so that its working area follows a circular path will prevent or to a large degree eliminate the danger of scuiing or marring which is present when the tool is moved in a rectilinear path or swung in a Curved arcuate path which is an incompletecircle. This is believed to be due to the blending action of the tool moving in a circle and rotating about an axis.

In order to carry out theprocess, tool- I6 is shown as comprising a casing |8 which in Figure 1 is illustrated as having an apertured upper end provided with a shoulder forming a seat for an outer ball race 22, the inner race 24I lbeing secured between an enlarged, shoulder-forming portion 26 of a shaft 28 and the hub 30 of a bevel gear 32 keyed to shaft 28. Ball bearings 34 space the races 22 and 24 from one another. A sleeve 36 positioned around the shaft below gear 32 has its lower end bearing against the inner race 38, of a ball bearing assembly, the outer race being received and supported in an eye 40 formed integral with the casing I8. The inner race 38 is, maintained in place upon the shaft 28 by means of an internal threaded collar 42 below the bearing assembly. A cap 44 is secured over the aperture in the upper end of casing |8vby means of cap screws 46 and. has an annular depending flange 48 which. serves to hold outer race 22 against shoulder 20.

Shaft 28 is driven through bevel gear 32 by means of a bevel gear 50 mating therewithand having a hub 52 keyed to a shaft 54 arranged at a right angle to shaft 28. Shaft 54 is supported for rotation within ball bearings 56V arranged at opposite ends of an enlarged portion of shaft 54. 'Ihe outer races of ball bearing 56 are supported by a tube 58 internally threaded at 60 and shouldered at 6 I- to receive an externally threaded collar 5`|` for holding one of bearings 56v in place against the shoulder 6|. Tube 58 is received in a circular aperture 62 formed in a` rear cover plate 64N and is clamped in place thereon by means of a press fit or by welding.

Rear cover plate 64 is also provided with an integral boss 10 provided with an internal bore 12 shouldered at 'I4 to provide a thrust face against which a ball bearing 16 is held by means of a sleeve 1.8, a second bearing race 80, and a plug 82 threaded into the boss 10; A shaft 84 is supported by bearings 'I6 and 80 and is provided.

with a thrust washer 86 held in place by a screw 88. The opposite end of shaft 84 carries, a gear cluster made up of a bevel gear 90 and driven gear 92, the cluster being keyed to the shaft and held in place thereon by a pin 94.

Gear 92 is adapted to be driven by a pinion 96 keyed to shaft 54 and spaced from inner bearing 56 and bevel gear hub 52 by collars 98 and |00.

Thebevel gear 90 meshes with a bevel gear |02 threaded upon a sleeve |04 and held in place by a set screw (not shown). Sleeve |04 is provided with an outwardly extending flange |06 at its lower end which provides a shoulder |08 between Which and the underside of the hub of bevel gear |02 a bushing |I0 ispositioned. Bushing |I0 has a pressed t in a cylindrical aperture ||2 in the lower portion of casing I8.y

Sleeve |04 is provided with an internal bore ||4 which is approximately 11s of an inch eccentric with respect to its outer cylindrical surface and is provided with a shoulder I|6 against which an upper ball bearing assembly H8 is located by means of sleeves |20 and lower ball bearing assembly |22 held in place by a sleeve |24 threaded into eccentric bore I4.

Shaft I4 is shouldered toward its lower end at |26 and has a collar |28 threaded upon its upper end to retain the bearings I I8 and |22 and sleeves |20 in place thereon. The upper end of shaft I4 is squared in cross section and has a disc |30 suitably secured thereto. The upper face of disc |30 is provided with a slot |32 in which a feather |34 on the lower face of an intermediate disc |33 is slidably positioned. The upper surface of disc |36 has an upwardly extending feather |38 which is slidably received in a slot in disc |40 fast to shaft 28. Feathers |34 and |38 are arranged at right angles to one another on opposite sides of the disc |36 and in conjunction with discs |30 and |40 form an Oldham coupling for transmitting power from shaft 28 to shaft I4.

It will be understood that power is received in the tool from .a exible shaft (not shown) coupled to shaft 54 or by a pneumatic or electric motor (not shown) which may be supported from. sleeve 58 in any suitable manner.

Due to the eccentricity of the borev ||4 with. respect to the axis of sleeve |04, it is evident' that shaft I4 carried in the bore I I4 is capable of moving in an orbit of 11g of an inch radius as the sleeve |04 is rotated by the bevel gear |02. At, the same time the shaft I4 may be rotated about its own axis by the Oldham coupling just described. I have found that if the ratio between` the speed of rotation of the shaft to the speed of rotation of the sleeve is set at or around 9 to. 1 the tool will give very satisfactory results. How-A ever, other ratios may be used effectively.

The path of the power transmitted throughv the tool may be traced from the shaft 54 through y bevel gears 52 and 32 at a 1 to l ratio to; shaft 28 are in a ratio of 1 to 3, the. cutting head. |0-

will be rotated and oscillated at the desirable speeds set out above.

A modified type of my tool is illustrated in f Figure 4. 'Ihe tool operates on the same principle as that shown in FiguresA 1 to 3 and consists of a casel2|8 having an internal boss 220 at its upper end recessed to receive the roller bearing assembly 222, 224, 234. The bearing journals the upper:v

end of shaft 228 for rotation within the case. The shaft is retained in the bearing by a washer and nut 226 secured to the top of the shaft.

Positioned around the shaft; 228 and. against the` underside of the inner race 224 of. the bearing assembly is a sleeve 236, the lower end of which rests on the hub 230 of a bevel gear 232 keyed to the shaft 228. 'Ihe hub 230 is supported from below on the inner race. 238 of a ball bearing assembly retained in an eye 240 formed integral with the case 2I8. The bearing is supported in the eye by an externally threaded ring 242' screwed into the eye below the bearing. Any upward4 thrust on shaft 228 is takeny by the bear-A ings 238 and 224 from a shoulder portion 244' formed` on theshaft. 228. The bevel gear 232 is driven by another bevel gear 250 having a hub 252 pinned to the shaft 254. The shaft 254 is journaled in ball bearings S retained in a sleeve 258 yat each end of an enlarged portion of the shaft 254. The bearings are further yheld in spaced relationship by a sleeve 259 fitted between them. An externally threaded annular ring 251 is threaded into the internally threaded end portion 25D of the sleeve 258 to hold the sleeve 259 and bearings 255 against a shoulder 26| formed on the inner end of the sleeve. The sleeve 258 is press fitted or otherwise suitably secured in an aperture 262 formed inthe boss 24| of the plate 284. The plate 254 is bolted to the side of the casing 2I8 and serves to close the casing.

The plate 254 is provided with an integral boss 21B provided with an internal bore 212 shouldered -at 214 to provide a thrust face against which a `ball bearing 216 .is held by means of sleeves 218 and a second ball bearing 280 and a cover 282 bolted or otherwise suitably secured to the open end of the boss 21E. A shaft 284 is supported by bearings 21E and 230 and provided with a thrust washer 286 held in place by a screw 288 threaded into the end of the shaft. The opposite end of the shaft 284 has a bevel gear 290 cut thereon and has the driven gear 292 keyed to the shaft just behind the bevel gear.

Gear 292 is arranged to mesh with and be driven by a driving gear 295 cut in the hub 252 of the bevel gear 250 carried on the upper shaft 254. A sleeve 243 spaces the hub 252 from the roller fbearing 255.

The bevel gear 290 mates with another bevel gear 302 threaded upon a sleeve 304 and is held in place by a set screw (not shown). Sleeve 304 is rotatably supported in a bushing IIO which is the same as the bushing III) shown in Figures 1 to 3 and the bevel gear operates to rotate a shaft I4 in Aan orbit about the shafts axis as in the first example of my invention. The shaft I4 is supported in the sleeve 364 in the same manner as in the rst example of my invention.

The major difference between the two examples of my tool is the means used to connect the shafts I4 and 228 and I4 and 28 which in the first example took the form of an Oldham coupling. In the example shown in Figure 4 I make use of a flexible shaft 336 secured at its ends to the adjacent ends of shafts 228 and I4. This i.

flexible cable imparts rotary motion to the shaft I4 while allowing it to swing in an orbit around its axis of rotation under the influence of forces applied to the bevel gear 352 through the bevel gears 290, 292 and the driving gear 296. rlhe tool chuck I2 will thus lbe given the same motion as in the first example of my invention.

It is obvious that the compound motion imparted to the grinding surface by my tool will prevent over finishing in any one spot and will relieve the operator from making so many motions. If so desired, the operator may continue to move the tool according to the old practice and obtain a greater degree of smoothness than was possible with older type of tools.

While I have described my invention in some detail, I intend this description to be in the nature of examples only and not limiting on my invention to which I make the following claims:

l. A grinding head comprising a case, a rst shaft journaled in said case, a second shaft extending through a wall of said oase, means for supporting said second shaft for rotation, means for rotating said rst mentioned means relative to said case about an axis other than the axis of said second shaft, means forming a driving coupling between said shafts, means for transmitting power to said rst shaft and to said rotating means, and a grindingttool secured to said second shaft.

2. A grinding head comprising a case, a rst shaft journaled in said case, Ia second shaft extending through a wall of said case, means for supporting said second shaft for rotation, means for rotating said first mentioned means relative to said case about an axis other than the axis of said second shaft, means forming a driving coupling between said shafts, means for transmitting power to said first shaft and to said second mentioned rotating means at dierent angular velocities, and a grinding tool secured to said second shaft.

3. A grinding head comprising a case, a rst shaft journaled in said case, a second shaft extending through a wall of said case, means for supporting said second shaft for rotation, means for rotating said first mentioned means relative to said case about an axis other than the axis of said second shaft, means forming a driving coupling between said shafts, means for transmitting power to said first shaft and to said second mentioned rotating means for rotating said last mentioned parts at a ratio of approximately 9 to l, and a grinding tool secured to said second shaft.

ll. A grinding head comprising a case having a bottom opening and a side opening, a shaft fixed for rotation within said housing and aligned with one of said openings, a rotatable member in said last mentioned opening, a second shaft journaled for rotation in said rotatable member and offset from the axis thereof, a cover plate for the second of said openings, a pair of drive shafts journaled in said cover plate, a pair of gears on each of said last mentioned pair of shafts, said pairs of gears being engaged and interconnecting said pair of shafts, one of said pair of gears `being connected to drive said shaft xed in said case and the other of said pair of gears being connected to said rotatable member, means for transmitting power between said shaft fixed for rotation in said case and said shaft in, said rotatable member, means for connecting a power source to oie of said shafts in said cover plate, anda grinding tool secured to said second shaft.

5. A polishing head comprising a case, a pair of parallel shafts journaled for rotation in a wall of said case, means for supplying power to one of said shafts, gears for interconnecting said shafts, a third shaft journaled for rotation in said case, gears for driving said third shaft from the shaft to which power is applied, a fourth shaft extend- `ing through a wall of said case, a journal for said fourth shaft, means for rotating said journal labout an axis other than the axis of said fourth shaft, means connecting said last mentioned means to the shaft of said pair of shafts to which power is not applied, means for driving. said fourth shaft from said third shaft, and `a polishing tool connected to said fourth shaft. i

6. A polishing tool comprising a case, a pair of parallel shafts journaled for rotation in a wall of said case, means for supplying power to one of said shafts, gears for interconnecting said shafts for rotation at a ratio approximating three to one between the driving and driven shaft, a third shaft journaled for rotation in said case, gears for driving said third shaft from the shaft to which power is applied at a one to one ratio, a fourth shaft extending through said casing, a journal for said fourth shaft, means for rotating said journal about an axis other than the axis of said fourth shaft, means connecting saidy last mentioned means to the shaft of said pair of shafts to which power is not applied in approximately a. one to three ratio, means connecting said third and fourth shafts for rotation in a one to one ratio, and a polishing member connected to said fourth shaft.

'7. A polishing tool comprising a case, a shaft journaled for rotation in said case, ya second shaft extending through a Wall of said case, ajournal for said second shaft, means for rotatingl said journal labout an axis other than the axis of said second shaft, means for driving said last mentioned means and said first shaft, means including an Oldham coupling for connecting said rst and secondshafts, and la polishing member secured. to said second shaft.

8f. A polishing head comprising a case, a shaft journaled for rotation in said case, a second shaft extending through a Wall of said case, a journal for said second shaft, means for rotating said journal about an axis other than the axis of said secondy shaft, means for driving said last mentioned means and said first shaft, means including a exible shaft for connecting said first shaft tov said second shaft, and a polishing tool connected to said second shaft.

DANIEL D. EYSTER. 

